EFFECTIVE OPERATOR CONTRIBUTIONS TO THE OBLIQUE PARAMETERS

We present a model and process independent study of the contributions from non-Standard Model physics to the oblique parameters S, T and U. We show that within an effective lagrangian parameterization the expre ssions for the oblique parameters in terms of observables are consiste nt, while those in terms of the vector-boson vacuum polarization tenso rs are ambiguous. We obtain the constraints on the scale of new physic s derived from current data on S, T and U and note that deviations in U from its Standard Model value would favor a scenario where the under lying physics does not decouple. (C) 1998 Published by Elsevier Scienc e B.V. All rights reserved.